The present invention relates to an intruder detection system which is useful for purposes of surveillance, or the detecting of the presence of an intruder or a change in the environment, of a predetermined area. In particular, the present invention is concerned with a space surveillance or intruder detection system utilizing pulsed microwave radar techniques in combination with signal processing logic for indicating when the environment of a secured area has been invaded or changed beyond certain predetermined limits.
The surveillance of secured areas has been carried out utilizing varying types of apparatus incorporating automatic electronic systems as well as systems requiring active human participation. Numerous types of systems have heretofore been known but have been fairly complex in terms of installation and/or operation. The installation has frequently required, among other things, elaborate preconditioning and adjustment to accommodate the ambient environmental conditions in the space under surveillance.
Representative prior art apparatus using radiated electromagnetic energy for intrusion detection will be found in the following patents:
U.S. Pat. No. 3,512,155 issued May 12, 1970 PA0 U.S. Pat. No. 3,697,989 issued Oct. 10, 1972 PA0 U.S. Pat. No. 3,733,602 issued May 15, 1973 PA0 U.S. Pat. No. 3,886,549 issued May 27, 1975 PA0 U.S. Pat. No. 3,932,871 issued Jan. 13, 1976 PA0 U.S. Pat. No. 3,938,118 issued Feb. 10, 1976 PA0 U.S. Pat. No. 3,943,503 issued Mar. 10, 1976
The particular features lacking in the known prior art relate to the ability of an automatic system of the present type to self-adapt to the environment in which it has been located. The absence of such self-adaptability inherently restricts the flexibility of the use and application of an automatic system such as has been achieved in the present invention. Also lacking is the ability to discriminate against certain types of variable signal conditions which selectively indicate an intruder's movement beyond certain range limits.